1. Field of the Invention
This invention relates to sulfonium salts, and more particularly to tris(disubstituted amino)sulfonium perfluoroalkoxides and -perfluoroalkylmercaptides, and to processes for their preparation.
2. Background
Tris(dialkylamino)sulfonium (TAS) salts of the formula EQU (R.sup.1 R.sup.2 N)(R.sup.3 R.sup.4 N)(R.sup.5 R.sup.6 N)S.sup..sym. X.sup..crclbar.
wherein each R is C.sub.1 -C.sub.20 alkyl having at least two .alpha.-hydrogen atoms and X is (CH.sub.3).sub.3 SiF.sub.2, Cl, Br, I, CN, NCO, NCS, NO.sub.2 or N.sub.3 are disclosed in U.S. Pat. No. 3,940,402. The TAS salts are soluble in organic liquids and are useful as polymerization catalysts and as reagents for replacing various groups in organic compounds with the group X.
Redwood and Willis, Can. J. of Chem. 43, 1893 (1965), disclose the trifluoromethoxides CF.sub.3 O.sup..crclbar. M.sym. (M.dbd.K, Rb, Cs) which are stable crystalline solids and are prepared by the reversible reaction of carbonyl fluoride and the appropriate metal fluoride. The salts are too insoluble in organic solvents to be characterized in solution. In the Can. J. of Chem. 45, 389 (1967) the same authors disclose the preparation of the higher perfluoro homologs (ethoxides, n-propoxides, isopropoxides, and n-butoxides) by reaction of the metal fluoride with an acyl fluoride or hexafluoroacetone. Spectroscopic evidence indicates that the alkoxides exist in equilibrium concentration with unreacted carbonyl compound in organic solution. No utility is disclosed for the compounds.
Downs. J. Chem. Soc. 1962, 4361, discloses the preparation of CF.sub.3 SAg and (CF.sub.3 S).sub.2 Hg by the addition of AgF and HgF.sub.2, respectively, to CF.sub.2 S.
Young, Fluorine Chemistry Reviews, 1, 359, 389-397, P. Tarrant, ed., M. Dekker, New York, 1967, discloses reactions of fluoride ion and polyfluoroalkyl anions, including the formation of perfluoroalkoxides and mercaptides. The formation of perfluoroalkoxides is an equilibrium reaction and isolation requires low temperatures to avoid excessive dissociation. The isolated salts are fairly stable but are extremely moisture sensitive. The alkoxides react with alkyl halides to form ethers.